Method of handling polymeric compositions



1 1953- H. A. BRUSON 2,649,356

METHOD OF HANDLING POLYMERIC COMPOSITIONS Filed Oct. 15, 1950 HEATEDSPINNING SOLUTION PORTION OF SPINNING SOLUTION TRANSFERRED TO CONTAINERFILLED CONTAINER COOLED TO SOLIDIFY SPINNING SOLUTION II I T T T T T T""1 SOLIDIFIED SPINNING SOLUTION STORAGE l SOLIDIFIED SPINNING SOLUTIONREMOVED FROM CONTAINER SOLIDIFIED SPINNING SOLUTION RETURNED TO HEATEDSYSTEM I AS REQUIRED lNVE/VTOR HERMAN A. BRUSON 2 ATTO NE) Fatented Aug.18, 1 953 METHOD OF HANDLING POLYMERIC COMPOSITIONS Herman A. Bruson,Shaker Heights, Ohio, assignor to Industrial Rayon Corporation,Cleveland, Ohio, a corporation of Delaware Application October 13, 1950,Serial No. 190,056

4 Claims.

This invention relates to the handling'of ethylene carbonate solutionsof acrylonitrile polymers. More particularly, it relates to aspin-solution handling process which permits the reclamation andrecovery of such polymeric solutions in a colorless condition and thuscapable of being reused to form acceptable fibers, filaments, films andthe like, hereinafter referred to as fibers.

Both prior to and during the extrusion of such spinning solutions into acoagulating medium, it is often found necessary to interrupt thecoagulation action and to setaside and collect the uncoagulated spinningsolution. There are various reasons for these interruptions such as, forexample, the following: (a) prior to extrusion it is the usual practiceto pump substantial quantities of the spinning solution through thespinneret until all of the impurities in the lines are removed and otherconditions such as temperature, viscosity, etc., have attained thedesired normalcy; (b) to adjust the spinning differences that mayexistfrom batch to batch of solution and from one spinning position tothe next; broken filaments or fibers; (d) to store excess quantities ofprepared spinning solution for future use. Such collected or storedspinning solutions are capable of being re-used to form acceptablefibers provided that efficient and noncolor-forming reclamation methodsare used.

The nature of the spinning solution is the principal source of thehandling and reclamation difficulties referred to above. When warm, thesolution is a viscous sticky syrup which sets to a rubbery, adherentplastic jelly at ordinary room temperature. It is very difiicult tohandle in that it sticks tenaciously to any surface, and therefore,cannot readily be removed from receptacles or containers in which it iscollected or temporarily stored. Furthermore, the use of heat forprolonged periods to remove such adherent material from receptacles,causes undesirable darkening of the polymeric material rendering itunsuitable for the spinning of fibers.

In accordance with the process of the present invention, not only canthe collected spinning solution be reclaimed and re-used to formcolorless fibers, but in addition, the containers for collecting orstoring the solution can also be re-used with practically no cleaningoperation. In accordance with the present invention, an ethylenecarbonate solution of certain acrylonitrile polymers which is beingextruded from a heated system through a spinneret while in a fluid stateis collected in a container, the walls of which slope inwardly towardthe bottom thereof, and the Collected material thereafter cooled to atemperature below about 20 C. The solidified material is removed fromthe container and later returned to the heated system from which it canbe extruded to form fibers. The polymeric solutions employed inaccordance with the present invention comprise ethylene carbonate and anacrylonitrile polymer dissolved therein having in the polymer moleculeat least about by weight acrylonitrile. The spinning solution containsbetween about 15 and 25% by weight of the polymeric material.

The spinning solution which has been cooled until solidified istransformed into a hard, tough, wax-like solid. This occurs attemperatures below about 20 C. and advantageously within the range ofabout +15 to -15 C'., and preferably, between about +5 and 5 C. Duringthis solidification, a certain amount of contraction and shrinkage inthe volume of the material ocours, and its adherence to smooth surfacessuch as metal surfaces practically completely disappears. The solid barof wax-like material can then be easily lifted or dumped out of thecontainer and added to new batches of spinning solution as desired.

The containers used for the purposes of this invention may be made ofany smooth-surfaced rigid material and of a wide variety of sizesdepending upon the quantity desired to be collected or stored.Particular advantages, however, are derived with containers made frommetal sheets, e. g., of stainless steel, aluminum, galvanized iron, etc.Preferably, the container and particularly the opening thereof should beof such a shape as to permit the easy removal of the solidifiedmaterial. As stated above, the walls of the container slope inwardlytoward the bottom thereof, and advantageously, may be shaped like a V orU, so that the resulting waxy bar easily falls out when the container isturned upside down and tapped.

The condition of the container after the removal of the waxy solidifiedmaterial is such that it may be re-used, i. e. refilled, immediately andrepeatedly without performing any polymer-= cleaning operation on thecontainer. Where hundreds of spinning positions of spinnerets are to beserviced each with an individual container, it is apparent that theprocess of the present invention provides substantial savings not onlyin initial equipment cost but also in material cost and in maintenanceexpenses. In addition, of course, it provides for the reclamation orstorage, or both, of spinning solution material in colorless spinnablecondition.

Thisinvention will be more fully described by 3 the following example,although it is understood that the invention is not intended to belimited by this example. In this example parts and percent of materialsis intended to mean parts and percent by weight.

Example 20 parts of polyacrylonitrile (average molecular weight about42,000) is dissolved in 80 parts ethylene carbonate by mixing and,heating to about 100 C. This solution after filtering and deaerating,under vacuum, is heated to 120 C. and extruded through a spinnerethaving 40 holes (.003 inch diameter). Prior to starting the actualextrusion into the coagulating bath, the extruded spinning solution iscollected in a stainless steel container having walls sloping inwardlyto the bottom thereof, i. e., U shape. This extrusion and collection ispermitted to continue at one spinning position until about 1000 grams ofmaterial is collected and substantially all of the impurities in thelines are removed and the temperature and viscosity of the solution haveattained the desired normalcy. Thereafter, the spinneret is plunged intothe bath liquid and the extruded spinning solution coagulated in a bathconsisting of 80 parts triethylene glycol and 20 parts ethylenecarbonate.

The 1000 gram portion of the spinning solution collected in thecontainer is placed in a refrigerator maintained at C. After one hour,the container is removed, the spinning solution having completelysolidified into a shrunken waxy solid. The container is then invertedand the solidified material is caused to fall therefrom by tapping thebottom of the container. The bar of solidified material is then added toa quantity of heated spinning solution and caused to dissolve therein.The resulting blended spinning solution is extruded and coagulated inthe coagulating bath described above. The emptied stainless steelcontainer is clean and free from particles of polymeric material. Thecontainer is then re-used for the same purpose and without any cleaningoperation. The bath temperature is maintained at 130 C. while thecoagulated filaments are drawn through the bath for 30 inches of bathtravel and then collected on bobbins rotating at a peripheral speed ofabout 4% meters per minute. The yarn is then washed, stretched andrelaxed to produce a final product which is light-colored and of uniformquality having a soft, silky feel, a denier of about 94, a breakingtenacity of about 4.4 grams per denier, and a breaking elongation ofabout 18%.

A previously stated, the acrylonitrile content of the polymer in thespinning solution is at least 80%, and particular advantages are derivedwith copolymers having a greater percentage of acrylcnitrile. Among thefiber-forming copolymers which may be employed with advantage inaccordance with the process of this invention y be mentioned cop lymersof acrylonitrile with the following monomeric compounds: vinyl esters(vinyl acetate, vinyl formats, vinyl benzoate), vinyl ethers, and vinylketones; acrylic acid and its esters and amides; methacrylic acid andits esters, amides, and nitrile; maleic, itaconic, fumaric, crotonicacids and their esters, amides and nitriles; ally-l alcohol and itsesters; styrene and nuclear substituted styrenes, e. g.

chloroand dichloro styrene; halogenated monoethylenic compounds such asvinyl chloride, vinyl fiuoride, and vinylidene chloride; N-ViI-lylpounds such as N vin yl pyrrolidone, N-vinyl suc- 4 cinimide, N-vinylcarbazole, 2- and ii-vinyl pyridine; and the like.

The acrylonitrile polymers and copolymers may be prepared by anysuitable polymerization method such as, for example, the ammoniumpersulfate catalyzed polymerization of monomer or monomers dissolved oremulsified in water. Molecular weights of these polymers and copoly-'mers are preferably within the range of 10,000

and 250,000, or even higher, although polymers having molecular weightsbetween 30,000 and 150,000 may be used with particular advantage in theproduction of fibers.

In general, the spinning solutions may be prepared by heating a mixtureof the finely divided acrylonitrile polymer or copolymer with theethylene carbonate solvent until the polymer is dissolved.Advantageously, the spinning solution may be maintained, prior toextrusion, at temperatures from about to 150 0., and preferably betweenabout and C.

The cooled and solidified material may be stored as such in thecontainers, or more advantageously may be removed and re-used directlyin preparing new batches of spinning solution or may be blended withsolutions undergoing spinning and coagulation. If desired, the so1idified material may be converted into smaller particles to facilitate thedissolving thereof. Under certain conditions, it may be desirable tostore the solidified material for future use either in bar form or in abroken form.

I claim:

1. A process for handling and reclaiming an ethylene carbonate spinningsolution of an acrylonitrile polymer which is being extruded from aheated system through a spinneret while in a fiuid state, the stepscomprising'collecting said material in a containerycooling said materialin said container to a temperature'below'about 20 C.; removing theresulting cooled and solidified material from said container; returningsaid solidified material to said heated system; reusing said containerfor the collection of additional quantities of said spinning solution,without performing any polymer cleaning operation on said emptiedcontainer between said emptying and refilling operations; said solutioncomprising ethylene carbonate and an acrylonitrile polymer dissolvedtherein having in the polymer molecule at least about 80% by weightacrylonitrile; said spinning solution containing between about 15 and25% by weight of polymeric material; the Walls of said container slopinginwardly toward the bottom thereof.

2. A process for handling and reclaiming an ethylene carbonate spinningsolution of an acrylonitrile polymer which is being extruded from aheated system through a spinneret While in a fluid state. the stepscomprising, collecting said extruded material in a container; coolinsaid extruded material in said container to a temperature between about+15 and -15 (1.; removing the resulting cooled and sohdified materialfrom said container; returning said solidified material to said heatedsystem and spinning fibers therefrom; re-using said containerfor thecollection of additional quantities of said spinning solution, withoutperforming any polymer cleaning operation on said. emptied containerbetween said emptying and refilling operations; said solution comprisingethylene carbonate and an acrylonitrile polymer dissolved therein havingin thepolymer molecule at least about 80% by weight acrylonitriie; saidspinning solution 5 containing between about 15 and 25% by weight ofpolymeric material; the walls of said container sloping inwardly towardthe bottom thereof.

3. A process for handling and reclaiming an ethylene carbonate spinningsolution of an acrylonitrile polymer which is being extruded from aheated system through a spinneret while in a fluid state, the stepscomprising, collecting said extruded material in a metal container;cooling and solidifying said extruded material in said container to atemperature between about +15 and 15 C.; inverting said cooled containerso as to cause said solidified material to fall therefrom; returningsaid solidified material to said heated system and spinning fiberstherefrom; re-using said container for the collection of additionalquantities of said spinning solution, without performing any polymercleaning operation on said emptied container between said emptying andrefilling operations; said solution comprising ethylene carbonate and anacrylonitrile polymer dissolved therein having in the polymer moleculeat least about 80% by weight acrylonitrile; said spinning solutioncontaining between about 15 and 25% by Weight of polymeric material; thewalls of said container sloping inwardly toward the bottom thereof.

4. A process according to claim 3 in which the container is a stainlesssteel container.

HERMAN A. BRUSON.

No references cited.

1. A PROCESS FOR HANDLING AND RELCLAIMING AN ETHYLENE CARBONATE SPINNINGSOLUTION OF AN ACRYLONITRILE POLYMER WHICH IS BEING EXTRUDED FROM AHEATED SYSTEM THROUGH A SPINNERET WHILE IN A FLUID STATE, THE STEPSCOMPRISING COLLECTING SAID MATERIAL IN A CONTAINER; COOLING SAIDMATERIAL IN SAID CONTAINER TO A TEMPERATURE BELOW ABOUT 20* C.; REMOVINGTHE RESULTING COOLED AND SOLIDIFIED MATERIAL FROM SAID CONTAINER;RETURNING SAID SOLIDIFIED MATERIAL TO SAID HEATED SYSTEM; REUSING SAIDCONTAINER FOR THE COLLECTION OF ADDITIONAL QUANTITIES OF SAID SPINNINGSOLUTION, WITHOUT PERFORMING ANY POLYMER CLEANING OPERATION ON SAIDEMPTIED CONTAINER BETWEEN SAID EMPTYING AND REFILLING OPERATIONS; SAIDSOLUTION COMPRISING ETHYLENE CARBONATE AND AN ACRYLONITRILE POLYMERDISSOLVED THEREIN HAVING IN THE POLYMER MOLECULE AT LEAST ABOUT 80% BYWEIGHT ACRYLONITRILE; SAID SPINNING SOLUTION CONTAINING BETWEEN ABOUT 15AND 25% BY WEIGHT OF POLYMERIC MATERIAL; THE WALLS OF SAID CONTAINERSLOPING INWARDLY TOWARD THE BOTTOM THEREOF.